As an electric motor repairman with years of experience, I would
like to start by saying "Don't soak an electric motor in anything."
Soapy water is among the worst things that can get into a motor.
Water makes conductors out of lots of things that don't conduct
electricity dry, and soap is an electrolyte.

If you can get by with it, don't do any cleaning other than air
blasts from a compressor nozzle, but not at too high a pressure.
While the motor is running, do short blasts through the end bell
vents, preferably from the shaft end only (the brushes are usually
in the other end, you don't want to disturb them).

For a motor with a wound armature and brushes it's okay to clean
the armature in mineral solvent after disassembly, but _no water,_
and you don't want any solvent near the bearings or lubricant
reservoirs (if any).  If the motor runs well, you want to avoid
disassembling it if possible.  Don't fix anything that isn't broken!

Lee Rothrock